https://blog.vladusenko.io/tags/rds/Recent content in Rds on Vlad Usenko's BlogHugoen-usFri, 10 Apr 2026 00:00:00 +0000https://blog.vladusenko.io/blog/rds-proxy-connection-pinning/Fri, 10 Apr 2026 00:00:00 +0000https://blog.vladusenko.io/blog/rds-proxy-connection-pinning/<p>We&rsquo;ve been having troubles with our Aurora MySQL cluster for a while: CPU distribution among read replicas was imbalanced, which led to application performance degradation.</p> <p>In this post I will share how we tracked down the root cause, solved it and what RDS Proxy had to do with it.</p> <h2 id="the-problem">The Problem</h2> <p>The system in question is a read-heavy service that uses Aurora MySQL as a database with RDS Proxy in between to allow faster failovers and safer maintenance activities. Traffic is stable most of the time, but there are a few days per month when we expect a surge of read operations to the service, due to which we scale up our Aurora cluster with read replicas preliminarily for a fixed period of time. However, we&rsquo;ve been seeing an issue with the CPU distribution among the replicas: it was completely uneven, almost random, some nodes were running on almost 99%, some on just a few.</p>